FIG. 1 is a perspective view of a wind turbine. As can be seen in FIG. 1, a wind turbine 1 that generates power by wind, which is a form of natural energy, includes a nacelle 3 installed on top of a tower 2, a hub 4 installed in front of the nacelle 3, and blades 5 installed at the hub 4. The wind turbine is generally a three-bladed design. That is, three blades 5a, 5b, and 5c are installed at the hub 4 at 120-degree intervals.
The nacelle 3 is connected to the hub 4 by a main shaft adapted to rotate together with the hub 4, and a speed-up gear connected to the main shaft and a generator connected to the speed-up gear are installed inside the nacelle 3.
The wind turbine 1 produces electricity using a generator as the main shaft rotates with the rotation of the blades 5, and torque of the speed-up gear connected to the main shaft is transferred to the generator inside the nacelle.
The blades 5 of the wind turbine 1 are connected to the hub while being connected to pitch bearings in order to change their angle of attack according to the wind speed. In general, the pitch of a blade can be changed in the range of 0 to 90 degrees.
Since the pitch of the blades 5 can be changed in the range of 0 to 90 degrees, the inner rings of the pitch bearings, which are worn by internal gears of the pitch bearings, should also be able to be changed in the range of 0 to 90 degrees, when the pitch of the blades 5 is changed.
When the inner rings of the pitch bearings of the blades 5 are worn in this limited range, the area of contact between the internal gears of the pitch bearings and the inner rings of the pitch bearings is changed from the range of 0 to 90 degrees (first section) to a range of 90 to 180 degrees (second section), a range of 180 to 270 degrees (third section), or a range of 270 to 360 degrees (fourth section), thereby extending the lifespan of the pitch bearings.
A pitch bearing repair process for changing the positions of the internal gears of the pitch bearings of the blades 5 consists of a process of removing all of the three blades 5a, 5b, and 5c from the hub 4, changing the positions of the inner rings of the pitch bearings, and then reassembling the three blades 5a, 5b, and 5c to the hub 4.
Since the three blades 5a, 5b, and 5c connected to the hub 4 are large, the process of removing the blades 5a, 5b, and 5c from the hub 4 and reassembling them is not easy and it takes a lot of time for repair.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.